Gabriela ate 5 slices of pizza. William ate 4 slices. If there were initially 10 slices, what fraction of the pizza was eaten?
Explanation: $\text{fraction of pizza eaten} = \dfrac{\text{number of slices eaten}}{\text{number of slices total}}$ They ate ${9}$ out of $10$ slices. They ate $\dfrac{9}{10}$ of the pizza.